Amazon.com’s holiday sales had the strongest day in its 10-year history on strong demand for electronics and books during the holidays.

Wal-Mart Stores said December sales at its American discount stores are rising about 2% as shoppers completed their Christmas purchases.

Amazon.com said it set a single-day record of more than 2.8 million orders, or about one-third more than its holiday record last year. Wal-Mart’s same store sales this month through December 24 are “in the middle” of the forecast gain of 1% to 3%. Shares of gadget retailer Sharper Image plunged after disappointing holiday sales prompted it to cut profit forecasts.

DVD players and digital cameras were among the top sellers atAmazon.com, which ran out of Apple Computer’s $299 20-gigabyte iPod music player and extended its deadline for orders with standard shipping by two days. More shoppers visited Wal-Mart stores compared with a year earlier, boosting sales after a sluggish beginning to the month.

“It’s going to be coming in within expectations,” said Michael Koskuba, who helps manage about $1.2 billion at Victory Newbridge in New York, including Kohl’s Corporation shares.

Target, the no. 2 American discounter, said December sales are rising within its forecast for a gain of as much as 5%.

American retail sales excluding automobiles and gasoline increased 8.1% between Thanksgiving and Christmas, according to MasterCard Advisors’ SpendingPulse report, which is based in part on MasterCard International transactions.

Amazon.com, the world’s biggest online retailer, didn’t specify which day set the record for holiday orders. The company also reported consumer electronics surpassed book sales during the Thanksgiving weekend, when it was its largest category for the first time.

The Seattle-based online retailer has been boosting the number of consumer electronics on its site during the last year, along with sharing revenue from sales of other retailers it allows to sell on its site. The company also drew customers by offering several short films featuring Hollywood directors and actors.

At its peak, Amazon.com hosted more than 700,000 visitors an hour, compared with the 630,000-visitor pinnacle it reached during the 2003 season. It also sold more than half a million gift certificates between November 25 and December 24.

The retailer reported selling more than one watch every minute since November 25 and tallying 13,000 orders for a “Lord of the Rings” DVD on December 13. Top-selling books included “America: A Citizen’s Guide to Democracy Inaction” by Jon Stewart and “The Five People You Meet in Heaven” by Mitch Albom.

Shares of Amazon.com rose $3.32, or 8.5%, to $42.25 in Nasdaq Stock Market composite trading, the biggest increase since July 2003.

Wal-Mart’s projected December gain at stores open at least a year is less than its 4.3% increase a year ago. Sales in November rose a less-than-expected 0.7% after the retailer offered fewer discounts the day after Thanksgiving to buffer margins.

Wal-Mart, the world’s biggest retailer, has since advertised about 24 items on which it cut prices or had prices lower than competitors.

Sales at stores that cater to middle-and lower-income shoppers have trailed those of luxury retailers amid higher energy prices and sluggish wage growth.

Sales of gift cards, which don’t count toward revenue until they are used, rose “significantly,” Bentonville, Ark.-based Wal-Mart said.

Wal-Mart rose 24 cents to $52.79 in New York Stock Exchange composite trading. They’ve fallen less than 1% this year. Minneapolis-based Target rose 81 cents to $51.31.

Sharper Image shares had their biggest decline in more than four months after merchandise shortages hurt fourth-quarter sales and the company cut profit forecasts.

The San Francisco-based retailer blamed ineffective advertising and a lack of “key holiday items” for the disappointing holiday results.

Sharper Image, which sells products such as robotic vacuum cleaners and massage chairs, expects fourth-quarter sales to rise 7% to 9% after forecasting a gain of as much as 18%. It estimates earnings of 94 cents to 99 cents in the fourth quarter after making $1.40 a year earlier.

Sharper Image shares fell $4.18, or 18%, to $18.96. Yesterday’s decline is the biggest since August 5 when shares fell 24% after Sharper Image cut its annual profit forecast.